a too ardent love. Therefore
adultery is in every kind of lust: and consequently it should not be
reckoned a species of lust.

Obj. 3: Further, where there is the same kind of deformity, there
would seem to be the same species of sin. Now, apparently, there is
the same kind of deformity in seduction and adultery: since in either
case a woman is violated who is under another person's authority.
Therefore adultery is not a determinate species of lust, distinct
from the others.

_On the contrary,_ Pope Leo [*St. Augustine, De Bono Conjug. iv; Cf.
Append. Grat. ad can. Ille autem. xxxii, qu. 5] says that "adultery
is sexual intercourse with another man or woman in contravention of
the marriage compact, whether through the impulse of one's own lust,
or with the consent of the other party." Now this implies a special
deformity of lust. Therefore adultery is a determinate species of
lust.

_I answer that,_ Adultery, as its name implies, "is access to
another's marriage-bed (_ad alienum torum_)" [*Cf. Append. Gratian,
ad can. Ille autem. xxxii, qu. 1]. By so doing a man is guilty of a
twofold offense against chastity and the good of human procreation.
First, by accession to a woman who is not joined to him in marriage,
which is contrary to the good of the upbringing of his own children.
Secondly, by accession to a woman who is united to another in
marriage, and thus he hinders the good of another's children. The
same applies to the married woman who is corrupted by adultery.
Wherefore it is written (Ecclus. 23:32, 33): "Every woman . . . that
leaveth her husband . . . shall be guilty of sin. For first she hath
been unfaithful to the law of the Most High" (since there it is
commanded: "Thou shalt not commit adultery"); "and secondly, she hath
offended against her husband," by making it uncertain that the
children are his: "thirdly, she hath fornicated in adultery, and hath
gotten children of another man," which is contrary to the good of her
offspring. The first of these, however, is common to all mortal sins,
while the two others belong especially to the deformity of adultery.
Hence it is manifest that adultery is a determinate species of lust,
through having a special deformity in venereal acts.

Reply Obj. 1: If a married man has intercourse with another woman,
his sin may be denominated either with regard to him, and thus it is
always adultery, since his action is contrary to the fidelity of
marriage, or with regard to